Intermolecular Hydrogen-bonding Interactions Research Articles

Sterically Tuned Ortho-Phenylene-Linked Donor-Acceptor Benzothiazole-Based Boron Difluoride Complexes as Thermally-Activated Delayed Fluorescence Emitters for Organic Light-Emitting Diodes.

Two donor-acceptor dyes with an ortho-phenylene-linked carbazole electron donor and a benzothiazole-fused boron heterocyclic acceptor were designed, synthesized, and spectroscopically investigated. Due to the steric effects of boron heterocyclic units, the dyes demonstrate different conformations in the crystalline state. The presence of numerous hydrogen-bonding intermolecular interactions and the very weak π-π stacking in the molecular packing results in intense solid-state emission with photoluminescence quantum yields of 40 and 18% for crystals and 50 and 42% for host-based light-emitting layers. The compounds show aggregation-induced emission and thermally activated delayed fluorescence (TADF). The received ionization potential and electron affinity values suggested good charge-injecting ability and bipolar charge-transporting properties of the developed dyes. Transport of holes and electrons was detected in layers of one dye by the time-of-flight measurements. The benzothiazole-based boron difluoride complexes showed high electron mobility of 1.5 × 10-4 and 0.7 × 10-4 cm2 V-1 s-1 at an electric field of 1.35 × 106 V cm-1. Therefore, these dyes were successfully applied as emitters in organic light-emitting diodes with external quantum efficiencies of 15 and 13%, respectively. Our study marks a critical advancement in the area of solid-state emissive boron difluoride dyes, which can be applied as TADF emitters into organic light-emitting diodes. The obtained results reveal that the orientation of the acceptor unit in the ortho-phenylene-linked donor-acceptor dyes makes a significant impact on the TADF activity.

Molecular dynamics simulations of hydrogen-bonded network structures of polybenzoxazines in the gas phase and aqueous solution

The crucial role of the amine functional group at the Mannich bridge of polybenzoxazines (PBZs) has been reported to be responsible for their hydrogen-bonded network structures. However, they have not been thoroughly studied in an aqueous solution and at the atomistic level. In this study, molecular dynamics simulations were applied to investigate the formation of hydrogen bond interactions of PBZs prepared from bisphenol A/methylamine (m-PBZ), bisphenol A/aniline-based (a-PBZ), and bisphenol A/2-(methylamino)ethylamine (e-PBZ). Based on the simulation results, the hydrogen-bonded network structures of the PBZs interfered with water molecules, leading to less compaction of the PBZ structure in the aqueous solution. The hydrogen bonding species of the m-PBZ and a-PBZ structures consisted of the –OH...N(Mannich) and –OH...O intramolecular interactions. However, for e-PBZ, the –OH...O species was not present, but the 2-(ethylamino)ethylamine substituent formed more hydrogen bonding species than those of m-PBZ and a-PBZ. Additionally, the intermolecular hydrogen bond interactions of the PBZs and water molecules were not detected in any of the aqueous solution simulations.

Intermolecular Hydrogen-Bonded Interactions of Oxalic Acid Conformers with Sulfuric Acid and Ammonia.

Oxalic acid is one of the simplest naturally occurring dicarboxylic acids that is abundantly found in the atmosphere, and it has several stable structural conformers. Hydrogen-bonded interactions of oxalic acid with other atmospheric molecules are important, as they might influence the chemical composition of the atmosphere, thereby impacting atmospheric chemistry and environmental processes. In this work, we used density functional calculations with the M06-2X/6-311++G(3df,3pd) model to examine the interaction of five oxalic acid conformers with sulfuric acid and ammonia-two widely recognized atmospheric nucleation precursor molecules-with the aim of observing the hydrogen-bonding characteristics of the conformers individually. An extensive and systematic quantum-chemical calculation has been conducted to analyze the structural, thermodynamical, electrical, and spectroscopic characteristics of several binary and ternary clusters mediated by five oxalic acid conformers. Our analysis of the electronic-binding energies and free energy changes associated with the formation of the clusters at ambient temperature reveals that multiple conformations of oxalic acid have the potential to engage in stable cluster formation in the atmosphere. In fact, the highest energy oxalic acid conformer exhibits the lowest bonding free energy in most cases. According to our calculations, clusters of oxalic acid with sulfuric acid demonstrate greater thermodynamic stability, a higher probability of formation, and more intense light scattering compared to clusters with ammonia. Furthermore, the analysis of successive cluster formation reveals that clusters formed between sulfuric and oxalic acids are more likely to grow spontaneously than those formed between ammonia and oxalic acid.

High proton conductivity of sulfonate-amine ionic HOFs and enhancement of SPEEK composite membranes.

Hydrogen-bonded organic frameworks (HOFs) are crystalline materials assembled by intermolecular hydrogen-bonding interactions, and their hydrogen-bonding structures are effective pathways for proton transport. Herein, we synthesize iHOF-45 using 4,4'-diaminodiphenylmethane and 1,3,6,8-pyrenetetrasulfonicacid sodium salt with 2D hydrogen-bonding networks. The introduction of ionic bond based on the weak hydrogen-bonding force was employed to enhance the stability of ionic HOFs (iHOFs). Thermal analyses demonstrated that iHOF-45 exhibited excellent thermal stability up to 332 °C. The proton conductivity of iHOF-45 was evaluated, demonstrating a notable increase with rising temperature and RH. At 100 °C and 98% RH, the conductivity reached 5.25 × 10-3 S cm-1. The activation energy (Ea) of iHOF-45 was calculated to be 0.281 eV for 98% RH, and the proton conduction was attributed to the Grotthuss mechanism, whereby the protons were transported in 2D hydrogen-bonding networks. Moreover, iHOF-45 was doped into SPEEK to prepare composite membranes, the proton conductivity of the 15%-iHOF-45/SPEEK membrane reached 9.52 × 10-2 S cm-1 at 80 °C and 98% RH, representing a 45.1% increase over that of the SPEEK. This suggests that doping enhances the proton conductivity of SPEEK and providing a reference for the development of high proton conductivity materials.

Molecule Empowerment and Crystal Desensitization: A Multilevel Structure-Property Analysis toward Designing High-Energy Low-Sensitivity Layered Energetic Materials.

Layered energetic materials (LEMs) can effectively balance energy and mechanical sensitivity, making them a current research focus in the field of energetic materials. However, the influence of the layered stacking pattern on impact sensitivity is still unclear, leading to the lack of advanced design strategies for high-energy low-sensitivity LEMs. Herein, we first utilize novel indicators such as maximum plane separation and hydrogen bond dimension to perform high-throughput screening on over 106 candidate structures, resulting in 17 target crystals. A systematic analysis was then conducted on the relationships between the bond dissociation energy (BDE) of the weakest energy-storing bond at the molecular level, the intralayer hydrogen bond energy (HBE), and the sliding energy barrier (SEB) at the crystal level with impact sensitivity. The findings suggest that a material can have low sensitivity only if at least two of the three properties perform well, and the interlayer sliding resistance can be reduced by enhancing the intermolecular hydrogen bond interactions, which reasonably explains the experimental phenomena. More importantly, we developed a prediction model for the impact sensitivity of LEMs with a coefficient of determination of 0.88. Additionally, factors affecting HBE and SEB were identified, and a linear model was established based on molecular-level feature variables. Finally, a new strategy for designing high-energy low-sensitivity LEMs was proposed, namely, empowerment at the molecular scale and desensitization at the crystal scale. This study integrates high-throughput screening, multilevel structure-property relationship analysis, and mathematical model construction, offering new perspectives for the development of novel high-energy and low-sensitivity energetic materials.

μ-Chlorido-bis-{[1-benzyl-3-(2,4,6-tri-methyl-phen-yl)imidazol-2-yl-idene-κC]silver(I)} chloride 1,2-di-chloro-ethane hemisolvate.

The title compound, [Ag2(C19H20N2)4]Cl·0.5C2H4Cl2, can be readily generated by treatment of (1-benzyl-3-(2,4,6-tri-methyl-phen-yl)imidazolium chloride with sodium bis-(tri-methyl-sil-yl)amide followed by silver chloride. The mol-ecular structure of the compound was confirmed using NMR spectroscopy and single-crystal X-ray diffraction analysis. The crystal structure of the title compound at 110 K has monoclinic (P21/c) symmetry. The represented silver compound is of inter-est with respect to anti-bacterial properties and the structure displays a series of weak inter-molecular hydrogen-bonding inter-actions with the chloride counter-anion.

Material synthesis, crystal structure, Hirshfeld surface and physicochemical characteristics Novel Stilbazolium crystal of 4-(2-(3-ethoxy-4-hydroxy-phenyl)-vinyl)-1-methyl pyridinium iodide (MEMPI) single crystal for NLO activity

In this study, a novel cation donor group 3-ethoxy-4-hydroxy benzaldehyde has been incorporated in the Stilbazolium cation with iodide anion to generate a new NLO activity of a single crystal of 4-(2-(3-ethoxy-4-hydroxy-phenyl)-vinyl)-1-methyl pyridinium iodide (MEMPI). The MEMPI crystal was effectively formed via the solvent evaporation technique. The structure and hydrogen bond interactions found in the molecule were determined by employing single-crystal X-ray diffraction. The compound crystallizes in the space group P21/c and monoclinic crystal pattern. The crystal structures are stabilized via intramolecular, intermolecular hydrogen bond interactions, C‒H···π, cation‒π, anion‒π, π···π stacking and lone pair-π interaction. In addition, a variety of O‒H···O, O‒H···I and C‒H···O interactions are also responsible for crystal packing. The 3D Hirshfeld surface and 2D fingerprint plots were used to examine the nature of intermolecular interaction. The 2D fingerprint maps indicate that the interactions between H···H contribute to 48.9 % of the total crystal stability. The newly synthesized material was characterized by 1H NMR and 13C NMR. In addition, the vibrational study of the synthesized molecule was performed using FTIR analysis. The grown crystal in linear optical characteristics were examined via a UV–Visible-NIR study. The photoluminescence (PL) activity of a MEMPI was studied with respect to the visible area and green colour emission was observed at 536 nm. The estimated CIE coordinates on the RGB colour gamut show the MEMPI crystal's ability to emit green light. The chemical etching approach was used to analyse the etch pit density and the growth habitat of the MEMPI crystal. The closed and open aperture Z-scan tests were carried out to determine the nature of third-order NLO susceptibility of the MEMPI crystal.

Molecular interaction between three novel amino acid based deep eutectic solvents with surface active ionic liquid: A comparative study

Interaction between a surface active ionic liquid (IL) viz. 1-decyl-3-methylimidazolium chloride [Dmim][Cl] with three novel amino acid-based deep eutectic solvents (DES, consisting of choline chloride and l-methionine (DES1), l-phenylalanine (DES2), and l-glutamine (DES3) in a 1: 2 mol ratio) is studied. Several techniques, including surface tension, fluorescence, UV–visible spectroscopy, and Fourier transform infrared (FTIR), were used to investigate the key micellar properties and intermolecular interactions between the IL and DESs. All the DESs studied here facilitate the micellization process successfully lowering the critical micelle concentrations (CMC) of [Dmim][Cl] with addition of 5 wt% and 10 wt% of DESs. In decreasing order of DES2 > DES1 > DES3, the affinity to promote IL [Dmim][Cl] aggregation within aqueous DES solutions. Additionally, the CMC values as well as the surface tension at CMC are both noticeably reduced significantly by DES2. The surface tension method determines how three amino acid-based DESs affect the CMC, Гmax, πCMC, Amin and pC20 of micellization. When IL [Dmim][Cl] forms micelles within DES solutions, the solvophobic effect predominates, and the intermolecular hydrogen-bond interaction helps to form micelles. FTIR was used to examine the molecular interactions and structural changes of the ionic liquid self-assemblies in aqueous DESs. The results show that the presence of DESs greatly aids in the micellization of [Dmim][Cl], and to a greater extent for DES2 than for DES1/DES3. The colloidal properties of DES and their mixtures are advantageous for the solubility, micellization, and other features of ionic liquids; further details on this positive observation are provided in the results and discussion. In the areas of micellization, CMC, synthesis, catalysis, and environmental, biological, and pharmaceutical applications, among others, DESs are extremely useful.

Photopolymerization initiated by p-diethylene glycol monomethyl ether cinnamyl formamide-based disulfide under 455 nm LED with minimized volume shrinkage

This study introduces a novel p-diethylene glycol monomethyl ether cinnamyl formamide-based disulfide monomer, N,N′-(disulfanediylbis(2,1-phenylene)) bis(4-(4-(2-(2-methoxyethoxy)ethoxy) phenyl)-2-oxobut-3-enamide) (Mp-BSCF), designed to reduce the volume shrinkage of photosensitive resins and initiate monomer polymerization under 455 nm LED light irradiation. The photochemical properties and photoinitiation efficiency of Mp-BSCF are systematically investigated using UV–vis absorption spectroscopy, electron paramagnetic resonance (EPR) and real-time infrared spectroscopy. Although its weak absorption around 455 nm, Mp-BSCF can generate arylthiyl radicals under 455 nm LED irradiation, and then effectively initiate the polymerization of triethylene glycol dimethacrylate (TEGDMA)/A glycerolate dimethacrylate (Bis-GMA) system. Increasing Mp-BSCF addition enhances the final double bond conversion and maximum polymerization rate of the TEGDMA/Bis-GMA system, reaching up to 82.0 % and 2.02 % s−1, respectively. Notably, Mp-BSCF significantly reduces the volume shrinkage of the photopolymerization system, with the addition of 10 % Mp-BSCF resulting in a 50 % reduction compared to the control system. This reduction is attributed to the dynamic reversible nature of the SS bond “breaking-recovery” and the intermolecular hydrogen bond interaction. Additionally, Mp-BSCF improves the thermal stability, friction resistance, and hardness of the TEGDMA/Bis-GMA photopolymerization system.

Chlorido-[(1,2,5,6-η)-cyclo-octa-1,5-diene](1-ethyl-4-isobutyl-1,2,4-triazol-5-yl-idene)rhodium(I).

A new neutral triazole-based N-heterocyclic carbene rhodium(I) complex [RhCl(C8H12)(C8H15N3)], has been synthesized and structurally characterized. The complex crystallizes with two mol-ecules in the asymmetric unit. The central rhodium(I) atom has a distorted square-planar coordination environment, formed by a cyclo-octa-1,5-diene (COD) ligand, an N-heterocyclic carbene (NHC) ligand, and a chlorido ligand. The bond lengths are unexceptional. A weak inter-molecular non-standard hydrogen-bonding inter-action exists between the chlorido and NHC ligands.

Self-Healing B ← N-Based Hydrogen-Bonded Organic Framework for Exclusive Recognition and Separation of Toluene from Methyl-Cyclohexane.

The effective separation of aromatic and aliphatic hydrocarbons remains a notable challenge in the petrochemical industry. Herein, we report a self-healing three-dimensional B ← N-based hydrogen-bonded organic framework (HOF), BN-HOF-1, constructed from discrete B ← N inclusive dimers through weak C-H···F and C-H···N hydrogen-bonding interactions. To make use of the specific recognition of the B ← N inclusive dimers for the toluene molecules and the reversible ad/desorption nature of this novel HOF, BN-HOF-1 can exclusively recognize and separate toluene from the mixtures of toluene-methylcyclohexane, thus generating 99.6% pure toluene from its mixtures after gentle heating, the recorded value among any reported materials for toluene purification. After the toluene molecules were released from the framework, it becomes the condensed BN-HOF-1a, which can be further reused for the highly selective recognition and purification of toluene from its binary mixtures, through the reversible structural recovery back to BN-HOF-1. Single-crystal X-ray diffraction and molecular modeling studies reveal that the high specific toluene recognition is attributed to the complementary electrostatic potential between the host B ← N inclusive dimers and the guest toluene, while the self-healing and recovery nature of this HOF is attributed to weak intermolecular hydrogen-bonding interactions.

Propolis ethanol extract functionalized chitosan/Tenebrio molitor larvae protein film for sustainable active food packaging

The application of novel insect proteins as future food resources in the food field has attracted more and more attention. In this study, a biodegradable antibacterial food packaging material with beneficial mechanical properties was developed using Tenebrio molitor larvae protein (TMP), chitosan (CS) and propolis ethanol extract (PEE) as raw materials. PEE was uniformly dispersed in the film matrix and the composite films showed excellent homogeneity and compatibility. There are strong intermolecular hydrogen bond interactions between CS, TMP, and PEE in the films, which exhibit the structure characteristics of amorphous materials. Compared with CS/TMP film, the addition of 3 % PEE significantly enhanced the elongation at break (34.23 %), water vapor barrier property (22.94 %), thermal stability (45.84 %), surface hydrophobicity (20.25 %), and biodegradability of the composite film. The composite film has strong antioxidant and antimicrobial properties, which were enhanced with the increase of PEE content. These biodegradable films offer an eco-friendly end-of-life option when buried in soil. Composite films can effectively delay the spoilage of strawberries and extend the shelf life of strawberries. Biodegradable active packaging film developed with insect protein and chitosan can be used as a substitute for petroleum-based packaging materials, and has broad application prospects in the field of fruits preservation.

Vibrational analysis, DFT computations of spectroscopic, non-covalent analysis with molecular docking and dynamic simulation of 2-amino-4, 6-dimethyl pyrimidine benzoic acid

Vibration assignments were refined through the use of normal coordinate analysis (NCA), one of several spectroscopic computations employed in extensive investigations into the composition of 2-amino-4,6-dimethylpyrimidine benzoic acid (2ADPB). Red-shifting bands revealed N-H-O hydrogen bonding, which is corroborated by optimised geometry results and vibrational analysis. The bond length and angle have been studied through an optimized geometry at B3PW91/6–31 G (d, p) theory. FMO and NBO methods investigate chemical reactions and strength of 2ADPB. Strong intermolecular hydrogen bond interactions O13‧‧‧H27-N25 and O14-H15‧‧‧N16 have been confirmed by structural studies and remains confirmed through BCP on H15-N16, H27-O13 for 2ADPB have sturdy intermolecular hydrogen bonds interactions. MEP categorizes negative and positive sites, visualizing charge accumulation on individual atoms in the molecule. The molecule showed charge transfer, analyzed with descriptors like LOL and ELF. Kirby-Bauer method confirmed findings across bacterial strains. Molecular Docking explored ligand-protein interactions, while pharmacokinetics was studied using drug features.

Crystal structures of 1,1'-bis-(carb-oxy-meth-yl)-4,4'-bipyridinium derivatives.

The crystal structures of 2-[1'-(carb-oxy-meth-yl)-4,4'-bi-pyridine-1,1'-diium-1-yl]acetate tetra-fluoro-borate, C14H13N2O4 +·BF4 - or (Hbcbpy)(BF4), and neutral 1,1'-bis-(carboxyl-atometh-yl)-4,4'-bi-pyridine-1,1'-diium (bcbpy), C14H20N2O8, are reported. The asymmetric unit of the (Hbcbpy)(BF4) consists of a Hbcbpy+ monocation, a BF4 - anion, and one-half of a water mol-ecule. The BF4 - anion is disordered. Two pyridinium rings of the Hbcbpy+ monocation are twisted at a torsion angle of 30.3 (2)° with respect to each other. The Hbcbpy monocation contains a carb-oxy-lic acid group and a deprotonated carboxyl-ate group. Both groups exhibit both a long and a short C-O bond. The cations are linked by inter-molecular hydrogen-bonding inter-actions between the carb-oxy-lic acid and the deprotonated carboxyl-ate group to give one-dimensional zigzag chains. The asymmetric unit of the neutral bcbpy consists of one-half of the bcbpy and two water mol-ecules. In contrast to the Hbcbpy+ monocation, the neutral bcbpy mol-ecule contains two pyridinium rings that are coplanar with each other and a carboxyl-ate group with similar C-O bond lengths. The mol-ecules are connected by inter-molecular hydrogen-bonding inter-actions between water mol-ecules and carboxyl-ate groups, forming a three-dimensional hydrogen-bonding network.

Controlling intermolecular interaction and interphase chemistry enabled highly stable aqueous ammonium-ion batteries

Aqueous ammonium-ion batteries (AIBs) show great potential in the large scale energy storage systems due to the advantages of low cost, high safety and environmental friendliness. However, they face the challenges of low output voltage and unsatisfactory electrochemical performance because of the narrow voltage window and unstable interfacial structure in conventional aqueous electrolytes. Herein, we design an aqueous AIB based on hydrogen-bond anchored electrolyte, Mn-based Prussian blue analogues (MnHCF) cathode and NaTi2(PO4)3@carbon (NTP@C) anode. In this electrolyte, the intermolecular hydrogen-bond interaction is constructed between water and sulfolane molecules, leading to the decreased water activity and wide voltage window. Furthermore, the coordination environment of NH4+ ions between sulfolane and CF3SO3- anions produces a unique solvation structure with low hydrated degree, which favors the formation of protective interfacial layer between electrode and electrolyte. Accordingly, the dissolution of MnHCF is largely inhibited and the side reactions between electrode and electrolyte are suppressed. As a result, the MnHCF electrode displays stable cycling performance and high Coulombic efficiency compared with the cases in conventional aqueous electrolytes. Moreover, the constructed full cells demonstrate high output voltage and superior stability. This work provides a synergistic route to design high-performance aqueous AIBs.

Synergetic effects of inter- and intramolecular hydrogen bonding interactions in XC5H3HC = Y···HO···H2O2 complexes (X = N, P, As and Sb; Y = O, S and NH): the role of aromaticity and exchange interactions

ABSTRACT Intramolecular hydrogen bonding (IHB) interactions were considered in XC5H3HC = Y···HO molecules which include OH···Y unit (Y = O, S and NH) and heteroatom X (X = N, P, As and Sb). Alteration of heteroatoms X in para position causes a change of properties of electron charge densities on these molecules and influences on strength of the IHB interactions. The aromaticity of the ring A (involving IHB interaction) and ring B (involving heteroatoms X) of XC5H3HC = Y···HO molecules was calculated using para-delocalisation index (PDI). Results reveal that the change of X from N to Sb is followed by the decrease in aromaticity of the mentioned rings. However, the strength of the IHB interactions increases during the change of X. Moreover, IHB energies were estimated using some computational methods and a viewpoint based on the properties of ring critical points (RCPs). The IHB energies obtained using a viewpoint based on the properties of RCPs have a better relationship with hydrogen bonding descriptors. Also, intermolecular hydrogen bond (HB) interactions of hydrogen peroxide with the close and open forms of the XC5H3HC = Y···HO molecules were considered. Cooperative effects of the HB and IHB interactions are revealed. Moreover, energy decomposition analysis (EDA) highlights the role of exchange interactions on the stability of the XC5H3HC = Y···HO···H2O2 complexes.

Characterization of hydrogel beads constructed from gelatinized lotus rhizome starch and sodium alginate by calcium cross-linking

The purpose of this study was to construct calcium cross-linked gelatinized lotus rhizome starch (LRS)/sodium alginate (SA) hydrogel beads of adjustable quality and to reduce the digestibility of gelatinized starch. LRS was mixed with SA, gelatinized by heating and subsequently cross-linked with Ca2+ to form hydrogel beads. The digestibility of the gelatinized LRS could be adjusted by changing the dose of SA in the hydrogel beads. When the LRS/SA ratio was 4/6, the rapidly digested starch (RDS) content in the beads was reduced by 26.9% compared with gelatinized LRS alone, whereas the slowly digested starch (SDS) and resistant starch (RS) contents increased by 12.3-fold and 2.3-fold, respectively. In addition, the water distribution in the Ca2+-crosslinked LRS/SA hydrogel bead samples also showed an SA dose dependence. With increasing SA concentration, the ability of the hydrogel beads to immobilize water increased. The diffusion of Ca2+ into the interpenetrating polymer network that was prepared with gelatinized LRS and SA gradually resulted in gelation dominated by ion bonds, leading to the heterogeneous microstructure of the hydrogel beads, which also involved intermolecular hydrogen bond interactions. Overall, the present study suggested a strategy for developing novel LRS hydrogel bead systems for quality control and gelatinized starch digestibility downregulation by adjusting the SA dose, which provided insights for the innovation of personalized and convenient starchy products in the food industry.

Screening ionic liquids based on COSMO-SAC model for extracting organic sulfur from coal and mechanism study

Screening suitable ionic liquids（ILs） for removing organic sulfur compounds from coal and discovering new, effective and environmentally friendly coal desulfurization additives is crucial. The solubility properties (SP) of six organic sulfur model compounds (OSMCs) in imidazole ILs were calculated based on the COSMO-SAC model. The results showed that 2-thiophenecarboxylic acid and 2-aminophenyl phenyl sulfone exhibited favorable solubility properties in certain ILs. The solubility properties of partial imidazole ILs consisting of [Cl]- were significantly better than other anions. Through the σ -profiles analysis of ILs anions, cations and OSMCs, it showed that [Cl]- had a higher tendency to be hydrogen bond acceptor than other anions. The polar groups in OSMCs increased the hydrogen bond donor or acceptor sites for interactions with ILs, while extended the optional range of ILs for hydrogen bond interactions with OSMCs. The extraction efficiencies of 2-thiophenecarboxylic acid by ILs were above 25%, with [DMIM][Cl] displaying the highest efficiency at 47.5%. Meanwhile, [DMIM][Cl] was the most effective extractant for removing all OSMCs except benzothiophene, which was basically consistent with the calculation results. Electrostatic potential analysis was used to obtain the sites where OSMCs are the most likely to form hydrogen bond interactions with [DMIM][Cl]. And characterization of hydrogen bond formation between ILs and OSMCs was obtained by FTIR analysis. The hydrogen bond formed by p-thiocresol with [DMIM][Cl] is weak, and the hydrogen bonds formed by 2-thiophenecarboxylic acid, 2-aminophenyl phenyl sulfone with [DMIM][Cl] are relatively strong. The analysis of intermolecular hydrogen bond interactions verified the mechanism underlying the excellent extraction performance for specific OSMCs by the selected ILs.

Packaged europium/fluorescein-based hydrogen bond organic framework as ratiometric fluorescent probe for visual real-time monitoring of seafood freshness

The freshness of sea food has always been the focus of attention from consumers, and food-safety issues are in urgent need of efficient approaches. A HOF-based ratiometric fluorescence probe (HOF-FITC/Eu) featuring superior amine-response, offers the real-time and visual detection of seafood freshness. Via intermolecular hydrogen bond interaction to form hydrogen-bonded organic frameworks (HOFs), which serve as a structural basis for the conjugate loading of pH-sensitive fluorescein (5-FITC) and coordination doping of lanthanide Eu3+. Amine vapors stimulate the dual-wavelength (525 nm and 616 nm) characteristic fluorescence of HOF-FITC/Eu with an inverse trend, resulting in an increase of the ratio of I525 to I616 accompanied by a distinct color transition from red to green. Prepared HOF-FITC/Eu featuring sensitive red-green color change characteristics of amine response are readily dripped into composite films of filter paper through integrated smartphone and 254 nm UV lamp as mobile observation devices to on-site monitor the freshness of raw fish and shrimp samples. The intelligent food probe HOF-FITC/Eu opens a novel material assembly type for fluorescence sensing and a potential pathway for other functional materials in the field of investigational food.

An effective ‘salt in dimethyl sulfoxide/water’ electrolyte enables high-voltage supercapacitor operated at −50 °C

Compared with organic electrolytes, aqueous electrolytes exhibit significantly higher ionic conductivity and possess inherent safety features, showcasing unique advantages in supercapacitors. However, challenges remain for low-salt aqueous electrolytes operating at high voltage and low temperature. Herein, we report a low-salt (0.87 m, m means mol kg−1) ‘salt in dimethyl sulfoxide/water’ hybrid electrolyte with non-flammability via hybridizing aqueous electrolyte with an organic co-solvent of dimethyl sulfoxide (hydrogen bond acceptor). As a result, the 0.87 m hybrid electrolyte exhibits enhanced electrochemical stability, a freezing temperature below −50 °C, and an outstanding ionic conductivity of 0.52 mS cm−1 at −50 °C. Dimethyl sulfoxide can anchor water molecules through intermolecular hydrogen bond interaction, effectively reinforcing the stability of water in the hybrid electrolyte. Furthermore, the interaction between dimethyl sulfoxide and water molecules diminishes the involvement of water in the generation of ordered ice crystals, finally facilitating the low-temperature performance of the hybrid electrolyte. When paired with the 0.87 m ‘salt in dimethyl sulfoxide/water’ hybrid electrolyte, the symmetric supercapacitor presents a 2.0 V high operating voltage at 25 °C, and can operate stably at −50 °C. Importantly, the suppressed electrochemical reaction of water at −50 °C further leads to the symmetric supercapacitor operated at a higher voltage of 2.6 V. This modification strategy opens an effective avenue to develop low-salt electrolytes for high-voltage and low-temperature aqueous supercapacitors.